The Blatten Miracle (News from Switzerland)

The massive rock slide in the Lötschental (Canton Valais, Switzerland) on May 28 got everyone’s attention. A single person is missing. Is that a miracle?

The event of May 28, 2025, was catastrophic. Rocks falling from the Kleiner Nesthorn piled 81-meters-high on top of the Birch Glacier, which ultimately broke away and cascaded down the mountainside throwing millions of tons of debris, water, ice blocks, trees, into the Lötsch Valley, narrowly missing a highway and destroying 90 percent of the village of Blatten and a neighboring hamlet. Despite the sheer scale of the event, only one life was lost, tragic but almost miraculous.

The fact that so few came to harm was due, in large part, to decades of preparedness and the swift deployment of preventive measures. People and animals of this farming community were evacuated in time and roads were closed.

Perhaps the most iconic image of the mountain collapse of Blatten

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The event highlighted Switzerland’s ongoing vigilance in monitoring and mitigating risks associated not only with geological hazards but also the broader dangers posed by its steep and unstable mountain terrain, which has long been a challenge for residents and authorities alike. It has also had profound consequences for real estate developers as well, who are always seeking space to build in this tiny country.

Blatten destroyed.

Lessons learned

The media focused on the spectacular images, of course, but there is a historic dimension. Early warning systems have made life in the mountains safer, and these can be traced to another event that occurred over two hundred years ago, one that is still commemorated annually in the town of Goldau in Canton Schwyz.

The incident took place there at 5 pm on September 2, 1806, at the end of another rainy day. Nearly 40 million cubic meters of rock suddenly slid off of Mount Rossberg and tore down the mountainside with such force that it even rolled back up 200 meters on the opposite side of the valley. Within four minutes, Goldau was buried under up to 50 meters of debris resulting in the deaths of 457 people. “The mountain seemed to come alive, shaking and cracking, before it swallowed the village whole,” one witness reported. Besides the people, a total of 111 houses, 220 barns, and several churches, were buried in up to 50 meters of rock and earth. Debris crashed into nearby Lauerzer Lake, cutting its size by about one-sixth and setting off a deadly tidal wave. It was Switzerland’s greatest natural catastrophe.

News of Goldau’s demise quickly spread across Europe and became a media sensation. Many artists even came to the area to depict the devastation in dramatic drawings. According to Alois Fässler, who wrote about the event in 2002, it triggered the first great movement of solidarity inside the confederation, with over 160,000 francs raised to rebuild the town (a value of over 30 million today). The funds were used to rebuild the transit road, of course, and later, the Gotthard Railway line set up a station at Arth-Goldau rather than tunnel under it. So life came back to the region, but the mountain remained scarred to this day and occasionally, releases a stream of mud. The local landscape is oddly shaped, too.

Science at work

But the Goldauer Bergsturz also produced generations of geologists and engineers who studied the event and the risks pose by life in a mountainous region, where extreme weather and geological instability are frequent dangers. In 1834, one Karl Ernst Adolf von Hoff suggested that it was probably due to the layered structure of the mountain plus water infiltration from heavy rains weeks before the event. In fact, some individuals who knew the Rossberg had already predicted a geological event in the years and days prior. A local doctor named Carl Zay, who witnessed the slide, wrote a very detailed description of what he saw and had heard, like people moving away having seen crevasses on the mountain filling with water.

Alfred Heim (1849-1937), one of the leading Swiss geologists, did pioneering work on the structural mechanics of mountains and the composition of rock layers. His research provided crucial insights into how certain types of rock could lead to catastrophic collapses (see image), notably the Rossberg’s Nagelfluh, a composite sandstone much feared by mountain climbers. Heim explained that Nagelfluh has both loose and compacted sections that are particularly susceptible to slippage, especially in wet conditions or after prolonged periods of stress (it’s known as Herrgottsbeton or “God’s cement” in southern Germany).

Top: Alfred Heim’s drawing of the Goldau disaster: below: Nagelfluh rock, pretty for building, dangerous for mountain climbing.

And so, the Goldau tragedy became a pivotal moment in the evolution of scientific research into mountain stability and prompted the Swiss government to adopt a more structured approach to hazard management, integrating geological assessments into the planning and construction of infrastructure in the country’s mountainous regions. While huge landslides, avalanches, and flooding can hardly be prevented, Switzerland’s approach has been to monitor and mitigate as far as possible using advanced geological surveys, early warning systems, and avalanche monitoring programs.

Climate or Nature?

The above-mentioned Alfred Heim once said that “all mountains want to flatten out.” The warming climate, with drier winters, rapidly shrinking glaciers, and changing precipitation patterns could exacerbate the frequency and intensity of rock slides and avalanches in mountainous regions. But science is always hesitant to establish causalities. In an interview with the German ARD television, glaciologist Mylène Jacquemart who works in Sion, Canton Valais, was asked about this regarding the Lötsch Valley event. “It is difficult to directly attribute such events to climate change,” she responded with some hesitation. “While we can observe certain trends, establishing a direct causal link remains elusive. Sometimes parts of mountains break off, that is just geology, but what is important for risk management is the frequency of these types of events.”

Switzerland is not the alone facing the threat of “sliding mountains.” Traditionally, rockfalls, landslides, and even large-scale mountain collapses have been part of the Alpine landscape, but recent decades have seen a marked rise in both frequency and severity of these hazards, according to the ETH Technical University in Zurich. The warming climate leads to the thawing of ice that cements rocks together in mountain flanks. As temperatures rise, this permafrost melts, destabilizing rock faces and making them more prone to sudden collapse.

So the Blatten miracle should serve as a warning to many people who feel that scientists and other experts –or “elites”– are merely raising unnecessary alarms in order to secure their jobs or because they are in cahoots with some dark forces. If the authorities were able to prevent damage to life and limb at Blatten, it was thanks to an army of geologists who carefully studied the Goldau catastrophe and shaped the country’s ability to adapt to and mitigate geological risks. In 1806, priests and pastors did their best to console the people who had lost everything by NOT saying the dead had been sinners who deserved what they got. Meanwhile, the scientists were beginning to lucubrate about what had objectively happened to the Rossberg. The Lötsch Valley rock slide is a somber reminder that while progress has been made, the threat posed by the country’s dynamic and unpredictable landscape remains a challenge, one that Switzerland is still working to fully understand and manage.

What was lost at Goldau. 457 people and 323 animals died, 14 were saved, 206 had fled or were not in town, 11 homes lost, 4 churches and chapels, as well as 220 barns and stables.

More information:

For details on the Birch glacier collapse, click here. If you are heading to the Gotthard Tunnel you might want to stop off at Goldau to visit the new museum of the rock slide. For the next year, it will be showing Roman Kälin’s very vivid, 3-minute reenactment of the Goldau event, a short that was nominated for an award by the Visual Effects Society earlier this year.